The present invention relates to cross-over conversion in data transfer applications.
High speed data transfer between semiconductor devices in an electronic system may be achieved by the use of a serialiser/deserialiser (SerDes). In order to avoid the use of a plurality of parallel connections between devices, a single differential analogue path is used running at a high data rate. One exemplary arrangement is specified by IEEE 802.3/AE/P.
In general, the differential signal from a transmitter arrives at an Analogue-Digital converter (ADC) in a receiver. In one exemplary application of the invention, the ADC has thirteen levels and output provides a 3-bit binary output, together with a sign bit.
High speed data transfer techniques such as SerDes operate in data transfer intensive environments, such as super computers and switch or router back planes. Signal routing in such environments is not trivial. Thus, it may not be possible to preserve the physical alignment of the tracks running between devices without recourse to track cross-over. A cross-over may be provided by a through board via or other wiring techniques, but not without a detrimental effect on the transmission channel characteristic and potential lack of symmetry. An alternative would be to wire directly from transmitter to receiver and to deal with the resultant inversion by means of a cross-over switch at either the transmitter output or the receiver input. However, the introduction of such a switch at the high data rates envisaged in the applications of the present invention would be problematic.